Q: Can you recommend a Conductivity Meter for Measuring Stream Flow?
Hydro Turbine - Renewable Energy from Water
Subject: Conductivity meter
From: ‘David’
Date: Mon, July 20, 2009 1:39 am
To: <smallhydroblog@smallhydro.com>
Dear Dorado Vista,
Q: Can you recommend a portable conductivity meter that can assist in the measuring of flow in streams using the salt gulp method. Is there a limit to the maximum flow that can be assessed using this method. I’m interested in flows that range between 50 l/s to 1000 l/s.
Thanks,
David
— A: SmallHydro’s Conductivity Measurement Answer —
From: jess.blog@smallhydro.com
Sent: 21 July 2009 17:34
To: David
Cc: smallhydroblog@smallhydro.com
Subject: RE: Conductivity meter – suggestions.
David,
Take a look at SpecMeters.com for EC or dissolved salt meters.
That particular page has several EC meters that would work. For DoradoVista ranch work we use the “Field Scout” it is sturdy, easy to use and accurate. It will measure both Soils & Water too. There are some more Water specific units and even GPS based ones there too. You are likely just going to need the cheapest water unit you can find.
The dissolved salt pulse method likely has no physical limit, but the practical limit will be defined by your instruments sensitivity and the background of dissolved solids (Electrical Conductivity EC variation), the volume of salt should be just enough to see the distinctive EC increase/decrease pulse.
You will need to use fine ground salt to make sure it dissolves quickly into your brine solution. You also should be careful not to use too much salt as it will affect the biosphere if it is left to concentrate in stagnant pools. Too much salt can take a much longer time to clear out between readings too. Maybe you could try pre dissolving? Most streams carry some salts in them and as such you will need to measure the background Ec and variation as a baseline reference.
Another thing to watch for with this method will be turbulent eddies or swirls in the water streamlines as this will affect the accuracy of your readings. That means you should take several smaller pulses at several different measurement cross-sectional stream-flow positions. This averaging of multiple measurements will make sure your results are free of too much position dependant time measurement error.
Watch for boulders and channel anomalies that will cause these eddies. You will typically want the opposite of what Gold panners want, that is you want swift deep water. Therefore swift deep water outside bends and away from eddies caused by mid channel boulders. Longer measurement distance will cut down on these errors as long as you can clearly measure the distinct EC reading changes.
Would you be Ok with this thread in a post or question later?
Sincerely,
Jess
DoradoVista, Inc.
—
Jess,
Thanks for replying, I will have a look at the link you have sent.
Also more than happy for you to post this thread.
Thanks again,
David
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